1. Field of the Invention
This invention relates to an elevator control apparatus which is capable of estimating with a high degree of accuracy how crowded an elevator car becomes upon reaching each floor of a building.
2. Description of the Related Art
In conventional elevator apparatus with a plurality of elevator cars incorporated therein, group control operation is generally conducted. Examples of such group control operation include the allocation method. The allocation method is designed to improve the operation efficiency of, and shorten the waiting time for a car by an evaluated value for each car immediately after a hall call is registered, by selecting the car which has the best evaluated value as the car to be allocated, and by making only that car respond to the hall call.
However, at the time of the day when the traffic is heavy in a building, such as the beginning of working hours, lunch time or quitting time, the car to be allocated to the hall call may have been packed to its full capacity before it responds to the hall call. In that case, the car passes the hall call, and the allocation (forecasting) is determining to another car. Furthermore, even when the car reaches the hall, since the car is already crowded, all of the people who wait for the car may not be able to get on the car Such passage of the car or leaving of the passengers is not desirable because it prolongs the waiting time of the passengers who wait for the car.
To prevent occurrence of such phenomena, Japanese Patent Publication No. 47787/1987 discloses an elevator group-control apparatus which is designed to select as a car to be allocated a car which has the minimum general evaluated value when a hall call is registered. In that case, the general evaluated value is the sum of a waiting time evaluated value and a full packing evaluated value. The waiting time evaluated value is the sum of the squares of all the estimated waiting times obtained when each car is virtually allocated to the hall call. The full packing evaluated value is obtained by weighting the sum of the full packing probabilities (an index indicating the possibility that the car is packed to its full capacity) relative to all the hall calls which are obtained when each car is virtually allocated to the hall call.
Other techniques which are proposed to prevent occurrence of undesirable phenomena include an allocation method disclosed in Japanese Patent Laid-Open No. 177266/1984. This method uses as the above-described evaluated value an estimated value of a car load (or the number of passengers in the car). In another allocation method (proposed in Japanese Patent Publication No. 4748/1986, the car whose estimated value of the number of passengers exceeds a limited value is not allocated to the hall call.
When allocation of the car for a hall call is made on the basis of the estimated value of a car's crowdedness which will occur in the near future (hereinafter referred to as "an estimated car crowdedness"), the waiting time for the hall call can be shortened, and occurrence of undesirable phenomena, such as passage of the car due to full packing and leaving passengers behind, can be reduced.
However, if the estimated car crowdedness is inaccurate, the evaluated value no longer works as a reference value for the selection of the car to be allocated, making shortening of the waiting time for the hall call and prevention of undesirable phenomena impossible. Hence, accuracy of the estimated car crowdedness greatly affects the performance of the group control.
The above-described group-control apparatus which employ the estimated car crowdedness are designed to prevent passage of cars because of full packing. However, various other types of group control apparatus have also been proposed. For example, Japanese Utility Model Publication No. 43975/1987 discloses a method in which a hall call is not deleted to omit the task of re-operating registration of the hall call in a case where it is estimated, using the number of passengers who are waiting for the car, detected by a waiting passenger detector, and an estimated car load obtained by estimating the number of passengers who may get off the car at the floor to which the car call is made, that passengers may be left off. In another method, the least crowded car is allocated to the hall call made on the important floor on which there are executive rooms or rooms for distinguished guests. Japanese Utility-Model Laid-Open No. 135969/1981 describes a method in which the estimated value of the number of passengers who get on or can get on the car is informed to the passengers who wait for the car using an annunciator provided at the elevator hall. In these group control apparatus also, accuracy of the estimated car crowdedness greatly affects the performance of group-control.
Conventionally, the following two types of methods of estimating the car crowdedness have been proposed.
(A) The estimated number of passengers in the car is obtained for each hall by distributing the number of passengers in the car to the destination floors to which the car call is made, by adding the number of passengers who wait for the car at the hall, detected by the waiting passenger detector, to the number of passengers in the car and by subtracting the number of passengers for each of the destination floors to which the car call is made (see Japanese Patent Laid-Open No. 102044/1975, Japanese Patent Publication No. 35368/1979 and so on)
(B) With variations in the estimated value of the car load (proportion to the rated load) taken into consideration, the probability (the full packing passage probability) with which the fully packed car passes the hall and the probability (leaving off probability) with which passengers may be left behind are obtained for each hall from the estimated values of the numbers of passengers who get on and off the car before the car responds to the hall call and the number of passengers who can get on the car (disclosed in Japanese Patent Publication No. 47787/1987).
To improve the accuracy with which the estimated number of passengers in the car is estimated, the following methods (C) and (D) have been proposed.
(C) The number of passengers in the car is distributed by a predetermined rate to the floors to which the car call is made, and the number of passengers for each destination floor is detected. At that time, correction is made such that the sum of the numbers of passengers in the car which are distributed to the individual destination floors equals the number of passengers in the car (Japanese Patent Publication No. 24578/1979).
(D) Each time the number of passengers in the car or the status of the car call changes, the estimated number of passengers in the car for each destination floor is corrected, by which accurate estimation is made on the basis of the latest traffic (Japanese Patent Publication No. 35371/1979).
In the above-described method (A) , provision of the waiting passenger detector is the requirement. However, the waiting passenger detector is expensive and may not be provided on each floor. Accordingly, the following method (E) has been proposed.
(E) the number of passengers who wait for the car at the hall is estimated using a constant value determined in accordance with the past traffic demands, and the estimated number of passengers in the car is operated on the basis of the number of waiting passengers (Japanese Patent Publication No. 35372/1979).
However, since the accuracy with which the number of passengers who wait for the car at the hall is estimated is low in the above method (E), the accuracy with which the estimated number of passengers in the car is estimated does not improve. Hence, the following methods (F) to (H) have been proposed so as to achieve accurate estimation of the number of passengers in the car even when no waiting passenger detector is provided.
(F) The number of passengers who wait for the car is estimated on the basis of the duration of the hall call, and the estimated number of passengers in the car is operated using the obtained number of waiting passengers.
(G) The average traffic per unit time is estimated by measuring the traffic on the service floors, and the number of passengers who wait for the car is estimated using the average traffic and the estimated time required for the car to arrive. The estimated number of passengers in the car is determined using the obtained estimated number of waiting passengers (Japanese Patent Laid-Open Nos. 4583/1984, 182182/1984)
(H) The estimated number of passengers in the car is determined using the number of passengers who wait for the car at the hall which is input by the passengers themselves from the hall waiting passenger input device (Japanese Patent Laid-Open No. 1246710/1984).
Japanese Patent Laid-Open No. 275381/1989 discloses a group-control apparatus which selects the car to be allocated to the hall call on the basis of the operation conducted using the neural net corresponding to the neurons of the human's brain. However, no consideration is given to the improvement of the accuracy with which the estimated car crowdedness is determined.
As stated above, in the conventional elevator control apparatus, various elements, including the number of passengers in the car, the state of the car call, estimation of the numbers of passengers who get on and off the elevator at each floor the elevator stops, estimation of the number of passengers on each destination floor, the traffic on each floor, are taken into consideration in order to operate the estimated car crowdedness with a high degree of accuracy. However, estimation of these elements with ever-changing complicated traffic taken into consideration makes the operation expressions for the estimated car crowdedness more complicated. Now that there is a limitation to the human ability, complicated operation expressions make development of new operation expression which provide improved operation is difficult. Furthermore, detailed estimation increases the time required for the operation. This makes quick allocation of the car and forecasting of the estimated car crowdedness impossible.